Driving unit for electric knife



3 1967 F. ROSEN ET AL 3,300,857

DRIVING UNIT FOR ELECTRIC KNIFE Filed Aug. 28, 1964 4 Sheets-Sheet 1 FIG 6 L 10 INVENTORS FRANK ROSEN B HERBERT F. YOUNG WM 7W) ATTORNEYS 3 1967 F. ROSEN ETAL 3,300,857

DRIVING UNIT FOR ELECTRIC KNIFE Filed Aug. 28, 1964 4 Sheets-Sheet 2 INVENTORS FRANK ROSEN BY HERBERT F YOUNG WM 7K,

ATTORNEYS Jan. 31, 1967 ROSEN ET AL 3,300,857

DRIVING UNIT FOR ELECTRIC KNIFE Filed Aug. 28, 1964 4 SheetsSheet 5 l I I r 64 52 so 6 154A 54 5 FIG] 64 52A 42A 60 60B 52B 42 Y FRANK ROSEN HERBERT E YOUNG Ww 7 7M/ ATTORNEYS Jan. 31, 1967 ROSEN ET AL 3,300,857

DRIVING UNIT FOR ELECTRIC KNIFE Filed Aug. 28, 1964 4 Sheets-Sheet 4 INVENTORS FRANK ROSEN BY HERBERT E YOUNG ATTORNEYS United States Patent Ofilice 3,30%,857 Patented Jan. 31, 1967 3,300,857 DRIVING UNIT FOR ELECTRIC KNIFE Frank Rosen and Herbert F. Young, Mansfield, Ohio, assignors to Dominion Electric Corporation, a corporation of hio Filed Aug. 28, 1964, Ser. No. 392,886 14 Claims. (Cl. 30272) Our invention relates to electric power units for reciprocating a pair of adjacent parallel cutting blades, commonly referred to as electric knives. Our invention is of the same general class as the device shown in U.S. Patent No. 3,120,056 issued February 4, 1964, on Power- Operated Knife, and is distinguishable therefrom.

An object of our invention is to provide an efficient driving unit for alternately reciprocating two closely adjacent parallel cutting knives or blades.

Another object is the provision for obtaining an improved reciprocating action having maximum efiiciency.

Another object is the provision of improved means for translating rotary motion of an electric motor to two reciprocating motions alternately moving in opposite directions.

Another object is the provision of improved means for blowing out or ejecting foreign material inadvertently entering the housing of our driving unit.

Another object is the provision of an improved arrangement in a driving unit so distributing the mass or weight thereof as to facilitate the cutting action of knife blades driven by the unit.

Another object is the provision of improved means for readily mounting and demounting the cutting blades or knives from the driving unit. Another object is the provision for affording increased safety in the mounting and demounting of blades from our driving unit.

Another object is the provision of a driving unit for a pair of alternately reciprocal cutting blades or knives so constructed and arranged as to provide improved efficiency in operation and economy in maintenance.

Other objectsand a fuller understanding of our invention may be had by referring to the following description and claims, taken in conjunction with the accompanying drawings, in which:

FIGURE 1 is a longitudinal sectional view taken through our driving unit and looking in the direction of the arrows 1-1 of FIGURE FIGURE 2 is an enlarged detail view illustrating the mechanism for alternately reciprocating one of the knife blades and showing the mechanism in intermediate position between extreme forward and extreme rearward positions of the knife blade;

FIGURE 3 is a view somewhat similar to that of FIG- URE 2 but showing the mechanism in its position for the retracted or extreme rearward position of the knife blade actuated thereby;

FIGURE 4 is another view somewhat similar to that of FIGURE 2 and FIGURE 3 but showing the reciprocating mechanism positioned in its extended or extreme forward position of the knife blade actuated thereby;

FIGURE 5 is a plan view of our driving unit showing the lowermost portion thereof and taken along the line 5-5 of FIGURE 1;

FIGURE 6 is an enlarged detail viewshowing the eccentric portions of the mechanism for translating rotary motion of the motor to two reciprocating motions in alternate directions;

FIGURE 7 is an enlarged view of the two blade-engaging elements or parts which are alternately reciprocated in opposite directions to correspondingly move knife blades carried thereby;

FIGURE 8 is a view partially in section showing details of one of the blade-engaging elements shown in FIG- URE 7;

FIGURE 9 is a side view of the same blade-engaging element shown in FIGURE 8;

FIGURE 10 is an end view of the blade-engaging element shown in FIGURE 9 and looking in the direction of the arrows 10-10 of FIGURE 9;

FIGURE 11 is a view partially in section of the bladeengaging element shown in FIGURE 9 and illustrating a step in the mounting of a knife blade to the bladeengaging element;

FIGURE 12 is a view somewhat similar to that of FIGURE 11 but showing a subsequent step in the mounting of the blade to the blade-engaging element and shows the blade in final secured position; and

FIGURE 13 is a cross-sectional view of our driving unit taken through the line 1313 of FIGURE 1.

Our driving unit has a housing or casing indicated generally by the reference character 11. It comprises a lower shell 12 and an upper shell 13 which mate to provide an enclosed chamber. The shells 12 and 13 are preferably made of a molded plastic material which is an electric insulator. The shells are held together by screw bolts 16 and 17 engaged in oppositely disposed posts integral with the shells.

At the forward end of the shell 13 there is a screened opening 14 which permits air to enter the interior of the housing. Formed at the rear of the upper shell 13 there is a recess provided for accommodating the prongs or male elements attached to the electrical system within the housing. The electrical terminals in the recess 15 are adapted to be connected to a source of electrical energy. An electric motor 23 mounted in the housing and connected to said electrical system may be energized upon actuating of a switch lever 51 with the finger of the operator holding the unit. The rearward end of the housing is adapted to be grasped by the operator so that the index finger of the operator may readily operate the switch lever 51. As is readily apparent, the weight or mass of our unit is distributed in such manner that the greater mass or weight is at the forward end of the unit so as to aid in bearing down on the object cut by the reciprocating knife blades.

Formed in the lower shell 12 is an opening 22 for permitting the rearward end portions of a pair of knife blades 64 and 65 to be inserted therethrough and to be engaged by blade-engaging elements 42 and 43, respectively, mounted within the housing.

There are forward vents 18 and side vents 19 provided in the lower shell 12 for aiding in ventilating the interior of the housing and the cooling of the motor therein, and also for draining out of any foreign material inadvertently entering the housing with the blades.

There are two forward posts 20 and two rearward posts 21 integral with the shell 12 and extending upwardly therefrom. A front supporting bracket 24 is mounted to the posts 20 by screw bolts 29A. This bracket 24 is secured to the motor 23 at its forward end to support the motor in position. There is a rear supporting bracket 25 also secured to the motor 23. This bracket 25 has an offset upper portion 25A which is secured to the posts 21 by screw bolts 21A. The rear bracket 25 has forward portion 25B disposed closest to the electric motor. Extending between the portions 25A and 25B is the main portion of the bracket 25, the arrangement being such that the motor is securely carried on the posts 20 and 21 extending from the lower shell 12.

Mounted on the rotatable shaft of the motor at the forward end thereof is a fan 27. This fan 27 is such that it draws air through the screened opening 14 into the interior of the housing. It also blows air downwardly into the bottom shell 12 and upon the portion of the knife blades within the housing and also blows foreign material inadvertently entering the housing with the blades outwardly and forwardly through the opening 22. The inclination of the fan blades is such that a draft of air is maintained so as to blow any such foreign material drawn into the housing by the blades outwardly of the housing through the forward opening 22 and thus maintains a clean condition within the housing.

Mounted onthe rearward end of the rotatable shaft of the motor 23 is a worm or spiral gear 26 which is arranged to rotate on its axis as the motor is energized The worm 26 is engaged with the teeth of a worm gear 31 whereby rotation of the worm 26 causes rotation of the gear 31, the axis of the gear 31 being in a plane normal to the axis of the rotatable Worm 26. Extending out from the worm gear 31 parallel to the axis thereof but offset from the axis are eccentric pins 32 and 33. The axes of the pins 32 and 33 are at 180 degrees from each other on opposite sides of the axis of the gear 31 as the gear 31 is rotated by the worm 26,

The outer ends of the eccentric pins 32 and 33 are mounted in roller discs 34 and 35, respectively. The pin 32 may rotate within the opening provided in the disc 34 and the pin 33 may rotate within the opening provided in the disc 35. The disc 34, gear 31 and disc 35 are on a common axis. As seen in the drawings, the eccentric pin 32 is mounted eccentrically relative to the axis of the roller disc 34 and the pin 33 is mounted eccentrically relative to the axis of the roller disc 35.

Carried by the bracket portions 25A and 25B of the bracket 25 and secured thereto by screw bolts 36 are a pair of bearing members 28 and 29. The bearing members 28 and 29 are preferably of bronze or other suitable type of metal to provide a good bearing engagement with the respective roller discs 34 and 35. Disc 34 is rotatively mounted in a recess provided in the side of bearing member 28 and disc 35 is rotatively mounted in a recess provided in the side of bearing member 29. The roller discs 34 and 35 may freely rotate on their common axis relative to the bearing members 28 and 29 which support the roller discs 34 and 35. It is thus seen that the hearing members 28 and 29 support the gear 31 so as to permit the gear 31 to freely rotate on its axis by reason of the bearing support provided to the roller discs 34 and 35 by the bearing members 28 and 29, respectively. In such rotation of the gear 31, the pins 32 and 33 revolve around the axis of the gear 31, the axes of the pins 32 and 33 being 180 degrees out of phase with each other.

Pivotally carried by the bracket 25 and extending out from the rearward end of the motor 23 are a pair of rocker arms 38 and 39. These rocker arms 38 and 39 are carried by pivot pins 40 and 41, respectively, which extend through the arms intermediate the ends of each arm. The pivot pins 4% and 41 are carried by an enlarged portion 25C of the bracket 25 as best seen in FIG- URE 5. The disposition of the arms 38 and 39 is such that they may swing in planes parallel to each other on the common axis of the pivot pins 40 and 41.

The upper end portion 38A of rocker arm 38 is forked or provided with an open slot. Similarly, the upper end portion 39A of rocker arm 39 is forked or provided with an open slot. The forked or slotted upper end 38A accommodates the pin 32 on one side of the gear 31 and the forked or slotted upper end 39A accommodates the pin 33 on the other side of the gear 31 to provide a good hearing or sliding surface within the arms of the forking on end 38A. There is a sleeve 36 of bronze or other suitable material positioned on the pin 32 within the fork or slot. Similarly, there is a sleeve 37 of bronze or other suitable material carried on the pin 33 within the fork or slot of the upper end 39A. These sleeves 36 and 37 on the pins 32 and 33 are free to move up and down between the opposed walls of the open slot forming the fork on the respective ends 38A and 39A.

By reason of the eccentric path traveled by the pins 32 and 33, the upper ends of the rocker arms 38 and 39 are pivotally rocked back and forth as the pins 32 and 33 revolve around the axis of the gear 31. By reason of the out-of-phase disposition of the pins 32 and 33, the arms 38 and 39 are rocked in opposite directions as the gear 31 rotates. As the upper end 38A moves forwardly, the upper end 39A moves rearwardly, and contrariwise, as the upper end 38A moves rearwardly, the upper end 39A moves forwardly.

The lower end 38B of rocker arm 38 is forked or provideo. with an open slot, as shown, and similarly the lower end 293 of rocker arm 39 is forked or provided with an open slot, as shown. By reason of the pivot support provided by the pivot pins 49 and 41, the rocker arms 33 and 39 piv-otally swing on the common axis of pins 40 and 41, being rocked in alternately opposite directions. That is, as rocker arm 38 swings in one direction, rocker arm 29 swings in the opposite direction. As the upper end of each rocker arrn swings forwardly, the lower end of the same rocker arm swings rearwardly. C-ontrariwise, as the upper end of each rocker arm swings rearwardly, the lower end of the rocker arm swings forwardly, the two rocker arms being out of phase with each other so as to swing in diametrically opposite directions.

The two pairs of blade holders or blade-engaging elements 42 and 43 are carried on the lower shell 12 upon a lower slideway 50. This slideway 50 is secured by cement or other suitable means to the bottom wall of the shell 12. As seen in FIGURE 13, the slideway 50 has two parallel adjacent grooves for accommodating the respective blade-engaging elements 42 and 43 and which permit the blade-engaging elements 42 and 43 to move longitudinally on the slideway 50 within the housing.

There are a pair of forward posts 48 and a pair of rearward posts 49 carried by the bot-tom wall of the shell 12 and extending upwardly therefrom. The posts 48 of the forward pair of posts are on opposite sides of the blade-engaging elements 42 and 43 and the posts 49 of the rearward pair of posts are also on opposite sides of the blade-engaging elements 42 and 43. A crossbar 46 secured to the upper ends of the posts 48 extends across over the top of the pair of blade-engaging elements 42 and 43. Similarly, a crossbar 47 secured to the upper ends of the posts 49 extends across over the top of the pair of blade-engaging elements 42 and 43. There is a sliding fit between the lower surface of the Crossbars 46 and 47 and the top surface of the blade-engaging elements 42 and 43 so as to permit the blade-engaging elements 42 and 43 to freely slide forwardly and rearwardly relative to crossbars 46 and 47. Thus, the slideway 50, posts 48 and 49, and crossbars 46 and 47 together provide guiding means for guiding longitudinal movement of the blade-engaging elements 42 and 43 within the housing. This permits the blade-engaging elements 42 and 43 to freely reciprocate back and forth within the housing, the blade-engaging elements 42 and 43 moving in opposite directions in their reciprocating movements.

Extending laterally from one side of the blade-engaging element 42 is a pin 44. Also extending laterally in the opposite direction from the blade-engaging element 43 is a pin 45. Pin 44 carried by the blade-engaging element 42 is accommodated within the fork or open slot of the lower end 39B of rocker arm 38. Similarly, the pin 45 carried by the blade-engaging element 43 is accommodated within the fork or open slot of the lower end 39B of rocker arm 39.

It is therefore seen that as the rocker arms 38 and 39 are swung back and forth on their respective pivots by the gear 31, the blade-engaging elements 42 and 43 are reciprocated longitudinally of the housing; as the arms 38 and 39 swing in opposite directions, so too, the bladeengaging elements 42 and 43 move longitudinally in opposite directions. As blade-engaging element 42 moves forwardly, blade-engaging element 43 moves rearwardly.

Contrariwise, as blade-engaging element 42 moves rearwardly, blade-engaging element 43 moves forwardly.

Each blade-engaging element is adapted to have anchored thereto the rearward end of a cutting or knife blade. The major forward end portion of the knife blades, such as blades 64 and 65, are closely adjacent to each other and they are coupled to each other near their forward ends in a manner to permit their reciprocation in opposite directions and at the same time to maintain the forward ends closely adjacent to each other. The rearward end portions of blades 64 and 65 are somewhat spaced apart and sufiiciently to permit the rearward end portion of each blade to be mounted in its separate blade-engaging element. The rearward end portions of the blades are similar to each other in shape, the rearward end portion of blade 65 being similar in appearance to that of the rearward end portion of blade 64 shown in greater detail in the drawings.

As seen in FIGURES 11 and 12, for example, the rearward end of blade 64 is disposed at an acute angle to its longitudinal axis to form the angular end 64C. At the lower and angled end 64C, the terminus is rounded to form the rounded rear end portion 64B. Forwardly from this rounded end portion 64B there is provided a notch 64A. The shape and angularity of the surfaces of the blade 64 aid in the mounting of the rearward end portion of the blade in the blade-engaging element 42.

. The blade-engaging element 42 has a longitudinally extending bore or slot 52 therein for receiving the rearward end portion of the blade 64. Similarly, there is a bore or slot 53 in blade-engaging element 43 for receiving the rearward portion of blade 65. The entrance of the bore 52 is chamfered to provide the throat 52A to facilitate the entry of the rearward end of the blade 64 within the bore 52.

Mounted transversely of the blade-engaging element 42 there is a catch or engaging pin 54 which may move along its axis transversely of the element 42. This engaging pin 54 has a chamfered end 54A so disposed as to initially meet the rounded end 64B of blade 64. By a camming action, rearward movement of the rounded end 643 against the chamfered end surface 54A of the pin 54 pus-hes or thrusts the pin 54 along its axis in a direction outwardly of the blade-engaging element 42. A leafsp-ring 56 secured at one of its ends to the side of the bladeengaging element 42 by a rivet 58 resiliently urgesthe pin 54 inwardly and in the path of the blade 64. However, the resiliency of the spring 56 is overcome by the force of the end 64B of the blade cammingly pushing or thrusting aside the pin 54. As soon as the blade has moved from the position shown in FIGURE 11 to the position shown in FIGURE 12 to where the pin 54 may engage within the notch 64A of the blade 64, then the pin 54 moves back inwardly of the element 42 under the resilient urging of the spring 56. Thus in the position of FIGURE 12, the blade 64 is held firmly within the engaging element 42 by the pin 54 within the notch 64A.

Similarly, in the blade-engaging element 43 there is a catch or engaging pin 55 which has a chamfered end 55A which cammingly meets and engages the rearward end of blade 65, the engaging pin 55 also being urged inwardly by a leaf-spring 57 held by a rivet 59 to the end of the blade-engaging element 43.

Mounted in the bore 52 of blade-engaging element 42 there is a spring 60 having the configuration shown in the drawings. The forward end of the spring 60 is bent to form a slanted end surface and thus provide a camming forward end 60A. The rearward end 60B of the spring 60 fits within a transverse slot 52 B extending through the blade-engaging element 42. The upper surface of the end portion 60B engages under the top wall of the transverse slot 52B, as better seen in FIGURES 11 and 12. Intermediate the camming forward end 60A and the rearward end 60B, there is a crook or distorted portion 66C having the configuration shown in FIGURES 11 and 12. Extending through the blade-engaging element 42 athwart the bore 52 is a crosspin 62 which engages with the crook 60C of the spring 60 and aids in retaining the spring 60 within the blade-engaging element 42. To mount the spring 60 within the blade-engaging element 42, the spring 60 is moved longitudinally into the bore 52, under the pin 62, over the bottom wall of the bore 52 to where the rearward end 60B engages the wall of the transverse slot 52B as illustrated. Similarly, there is a spring 61 of corresponding shape mounted in the bore 53 of the blade-engaging element 43, a crosspin 63 correspondingly holding the spring 61 in anchored position. The bias of the springs 66 and 61 is such as to urge upwardly the cramming forward ends 66A and 61A, respectively. The forward end of the springs 66 and 61 engage and resiliently urge upwardly the bottom edges of the blades 64 and 65 at the location of the throats of the respective bores. The bias of the springs, however, may be overcome by the operator mounting the blades to the respective bladeengaging elements. Initially the blades are tilted downwardly at about the angle shown in FIGURE 11 and moved rearwardly to where the rearward end of the blades meet the respective engaging pins 54 and 55. The blade are then progressively moved rearwardly upon pressing aside the engaging pins, such as pins 54 and 55, to where the pins engage in the notches, such as notch 64A in blade 64. When the blade has been moved rearwardly to this rearwardmost location, then it i released against the tension of the spring 60 so that the blade 64 moves upwardly from its tilted position shown in FIGURE 11 to its aligned position shown in FIGURE 12, that is, where the longitudinal axis of the blade is parallel to the longitudinal axis of the blade-engaging element.

It is to be noted that in the cutting of objects with blades actuated by our device, the force against the object-being cut is such as to urge the rearward end portion of the blades downwardly and thus to firmly retain the notch 64A around the pin 54, a similar action being associated with the other blade. In this manner, the blades are urged into good locking position during the use of the device and accidental disengagement of the blades from the bladeengaging elements is resisted. The blades are disengaged by reversing the operation. The blade shown in FIGURE 12, for example, is tilted so as to press downwardly the forward end 60A of the spring 60 and thus to tilt the blade sufliciently that the notch 64A clears the pin 54. After the notched rearward end clears the pin 54, then the blade is pulled back sufficiently so as to be withdrawn from the blade-engaging element 42. The bias of the spring 60 resiliently opposes such a tilting action and thus tends to maintain the blade in its aligned position shown in FIGURE 12. By means of our improved structure, blades are readily mounted and demounted and at the same time, the blades are retained against accidental disconnection from the blade-engaging elements.

FIGURES 2, 3 and 4 illustrate the character and extent of movement which is obtainable with our device. In FIG- URE 2, the arm 38 and blade-engaging element 42 are shown in their intermediate position, that is, midway between forward and rearward limits of the element 42. In this view, the distance between the rearward end of the blade-engaging element 42 and a verical plane through the axis of the pivot pin 40 is' denoted by the letter XQ In FIGURE 3, wherein the rocker arm 38 and blade-engaging element 42 are in their retracted or most rearward position, the distance between the rearward end of the bladeengaging element 42 and the same vertical plane through the axis of the pivot pin 40 is denoted by the letter Y. In FIGURE 4, which shows the rocker arm 38 and bladeengaging element 42 in their extended or most forward position, the distance between the rearward end of the blade-engaging element 42 and the same vertical through the axis of the pivot pin 40 is denoted by the letter Z.

The longitudinal distance that the blade engaging element travels in equal to Z minus Y. It is understood, of course, that the action of the other rocker arm 39 and the other blade-engaging element 43 is similar but is out of phase with the movements of the arm 38 and element 42 so as to move in the opposite direction.

It will be recognized by those knowing the problems of devices of this kind that we have here produced a driving unit having improved safety features and which performs to give an efficient cutting action in the use of the device.

The present disclosure includes that contained in the appended claims, as well as that of the foregoing description.

Although this invention has been described in its preferred form with a certain degree of particularity, it is understood that the present disclosure of the preferred form has been made only by way of example and that numerous changes in the details of construction and the combination and arrangement of parts may be resorted to without departing from the spirit and scope of the invention as hereinafter claimed.

What is claimed is:

1. A device for driving in alternate longitudinal parallel reciprocation relative to each other a pair of adjacent cutting blades comprising in combination, a casing, an electric motor mounted in the casing, said motor having a rotatable shaft disposed longitudinally of the casing, a worm associated with said shaft to be rotated thereby, a worm gear carried by the casing and enmeshed with said worm to be rotated thereby, a pair of pins extending from opposite sides of said worm gear and eccentrically mounted relative to the axis of the worm gear to revolve therearound, the said pins being about 180 out of phase with each other in revolving around said worm gear axis, a pair of rocker arms each having first and second slotted portions at the opposite ends thereof, pivotal mounting means carried by said casing for pivotably supporting each rocker arm intermediate of its ends to permit the said opposite ends to swing in opposition to each other, the first slotted portions of said rocker arm accommodating said pins, respectively, to cause said arms to rock on said pivoted mounting means upon the revolving of said pins, said arms alternately rocking in opposite directions upon the revolving of said pins out of phase with each other, a pair of blade-engaging elements disposed generally parallel to each other and each being adapted to engage a said blade for actuating the same, guide means carried by the casing for guiding alternate reciprocal parallel movements of said blade-engaging elements, each of said blade-engaging elements having a pin extending therefrom and accommodated in the second slotted portions of said rocket arms, respectively, the alternate rocking of said arms in opposite directions causing said bladeengaging elements to reciprocate along said guide means in opposite directions whereby cutting blades engaged to the respective blade-engaging elements alternately reciprocate parallel to each other in opposite directions.

2. A device for driving a pair of cutting blades arranged for alternate reciprocal longitudinal movements parallel and adjacent to each other comprising in combination a housing, an electric motor carried by the housing, a pair of driving pins carried by the housing eocentrically mounted relative to an axis about which the pins revolve and disposed out of phase with each other relative to said axis, operating means operatively connecting the said motor and driving pins to drive said pins by the said motor, a pair of blade-engaging elements carried by the housing for engaging rearward end portions of a pair of cutting blades, respectively, for reciprocating said blades in opposite directions in parallel paths longitudinally of said housing, and a pair of rocker arms disposed to swing in generally parallel planes parallel to said parallel paths of said bladeengaging elements, pivot support means carried by said housing for providing pivotal support for said rocker arms to swing in .said generally parallel planes, each of said rocker arms being operatively connected to a said driving pin and to a said blade-engaging element for effecting longitudinal movement of the blade-engaging element upon the revolving of the driving pin by the swing of the respective rocker arm, said driving pins upon revolving out of phase with each other about said axis reciprocating said blade-engaging elements in said parallel paths in opposite directions 3. A driving unit for a pair of alternatively reciprocal parallel cutting blades comprising the combination of, a housing adapted to be held by the operator, an electric motor mounted in the housing and having a rotative shaft disposed generally longitudinally of the housing, a pair of blade-engaging elements carried by the housing each adapted to engage a rearward end portion of a said blade protruding into the housing for actuating the said blade, said elements being slidably mounted in said housing to reciprocally move in parallel paths disposed generally longitudinally of the housing, a pair of rocker arms pivotably supported in said housing to swing in planes disposed generally longitudinally of said housing, a pair of eccentric driving members driven by said motor drive shaft to revolve in circular paths and operatively connected to respective rocker arms of said pair of rocker arms to swing the same in said planes, said driving members being out of phase with each other to swing said rocker arms out of phase with each other, said rocker arms being operatively connected to respective blade-engaging elements to reciprocally move the same longitudinally of the housing upon the swinging of said rocker arms, said blade-engaging elements being reciprocally movable out of phase with each other by the swinging of said rocker arms out of phase with each other.

4-. A driving unit as claimed in claim 3 and in which said blade-engaging elements include locking means adapted to interengage with the rearward end portions of the respective blades for locking the said rearward end portion in the respective element, and spring means carried by the respective element urging the rearward end portion of the blade into interengagement with the locking means of said element.

5. A driving unit as claimed in claim 4 and in which said blade-engaging elements include cammin-g means engageable *by said rearward end portion of each blade for moving the locking means out of the path of the rear ward end portion upon insertion of the rearward end portion into the respective element.

6. A driving unit for a pair of cutting blades disposed adjacent each other and reciprocally movable in opposite directions comprising in combination, a portable housing adapted to be held by the operator, an electric motor mounted in the housing, a pair of blade-engaging elements reciprocally movable in the housing in paths generally parallel to each other and disposed longitudinally of the housing, said housing having a first opening at its forward end providing access to said elements so that the rearward end portions of a pair of blades may be inserted therethrough into engagement with said elements, said housing having a second opening at its forward end laterally spaced from said first opening providing ingress for air to enter said housing, a rotatable fan mounted in said housing at said forward end adjacent and to one side of said first opening, said fan being driven by said electric motor, said fan having fan blades disposed to draw air into the housing through said second opening and to impel said drawn air against the blades inserted into the housing through said first opening and to induce foreign material entering the housing with the blades through said first opening 'to be dischargd out of the housing through said first opening, and operating means carried by thehousing and driven by said electric motor for reciprocally moving said elements in opposite directions to reciprocally moving blades engaged thereto in opposite directions.

7. A driving unit as claimed in claim 6 and in which said operating means include a Worm rotatable by said motor, a gear rotatable by the worm, eccentric driving pins disposed 180 out of phase with each other and revolvable by said gear, pivotal rocker arms swingable in generally parallel planes by said driving pins in alternately opposite directions and connected to said elements for correspondingly reciprocally moving said elements in pposite directions.

8. A driving unit for actuating a pair of reciprocal cutting blades comprising the combination of, housing means, an electric motor mounted in the housing means, a pair of bladeen-gaging elements carried by the housing for engaging rearward end portions of said cutting blades, respectively, operating means driven by said motor for reciprocating said elements in opposite directions in parallel paths to actuate the blades engaged thereto, said housing having openings in the wall thereof at the forward end thereof providing access to said elements to permit the blades to be inserted into the housing to engage said elements, respectively, and to permit air to flow through the said housing wall, and fan blower means disopsed in said housing adjacent said forward end and adjacent said openings and driven by said motor, said fan blower means being arranged to draw air through a said opening at said forward end into said housing from the exterior thereof and to blow air against said blades inserted in said housing and out through another of said openings to eject with said air foreign material entering the housing with said blades outwardly of the housing through said another of said openings.

9. A driving unit as claimed in claim 8 and in which said fan blower is disposed generally rearwardly of one of said openings and forwardly of said motor to draw air through said one opening at said forward end into the housing against said motor for cooling the same and disposed generally alongside of the portions of said blades inserted in said housing to cause air flowing tangentially from the fan blower to blow in said housing athwart said blades within said housing and thence outwardly through said another of said openings.

10. A driving unit for actuating a pair of reciprocal adjacent cutting blades comprising the combination of, a portable housing adapted to be held by the operator, an electric motor carried by the housing and having a driving shaft disposed longitudinally of the housing, said housing being open at the front end thereof for permitting air to enter therethrough into the housing, a rotatable fan mounted on said motor shaft to be driven thereby forwardly of said motor and rearwardly of said open front end to draw air therethrough into the housing and against said motor for cooling the same, a pair of reciprocally movable blade-engaging elements carried by the housing for movement in generally parallel paths extending longitudinally of the housing, said elements being adapted to engage the rearward portions of cutting blades inserted through said open front end into the housing for reciprocating the respective blades engaged therewith, the rearward portions of the cutting blades being so spaced from the walls of the housing at the open front end thereof that foreign material may enter the housing through the open front end with the cutting blades, said rotatable fan being positioned in said housing to blow air drawn into the housing by the fan against the rearward portions of the cutting blades within said housing to blow foreign material entering the housing with said cutting blades forwardly out through said open front end in a direction longitudinally of said cutting blades, and operating means driven by said driving shaft rearwardly of said motor for reciprocally moving said blade-engaging elements along said parallel paths.

11. A driving unit as claimed in claim Hand in which said operating means includes out-of-phase portions arranged to move simultaneously in opposite directions to reciprocally move said elements in opposite directions for corresponding reciprocation in opposite directions the blades engaged therewith.

12. A driving unit as claimed in claim 10 and in which said rotatable fan has blades arranged to blow air tangentially thereof and the fan is disposed to direct such tangentially blow air against the rearward portions of the cutting blades within said housing.

13. Mechanism for translating a single rotary motion to a pair of simultaneous reciprocating oppositely directed motions, comprising the combination of a rotatable driving worm, a gear enmeshed with said worm to be rotated thereby, a pair of pins extending from opposite sides of said gear parallel to, and spaced from, the axis of said gear, said pins being on diametrically opposed sides of said axis, bearing means bearingly supporting said pins to permit the revolving of said pins in orbital paths around said axis as said gear is rotated by said worm, a pair of rocker arms disposed in generally parallel planes and pivotally mounted intermediate the ends thereof to provide for the swinging of opposite end portions of each rocker arm in opposite directions, a pair of elements disposed to move in parallel linear paths, guide means for guiding said elements in moving along said linear paths, first means connecting a first end portion of each of said rocker arms to each of said pins, respectively, for pivotally rocking the respective rocker arm upon the revolving of each said pin, and second means connecting an opposite end portion of each of said rocker arms to each of said elements for longitudinally reciprocating the respective element upon the pivotal rocking of each said rocker arm, said rocker arms being swung and associated said elements being longitudinally reciprocated in opposite directions by said pins disposed on diametrically opposite sides of said gear axis.

14. Mechanism as claimed in claim 13 and including attaching means carried by said elements for attaching cutting blades thereto, respectively, whereby said blades may be simultaneously reciprocated in opposite directions by said mechanism.

References Cited by the Examiner UNITED STATES PATENTS 1,732,945 10/1929 Novic 7453 1,738,365 12/1929 Gahagan 30339 2,293,637 8/1942 Bourque 30-216 2,316,985 4/1943 Niedermayer 30335 2,467,481 4/ 1949 Huff 30339 2,704,941 3/ 1955 Holford.

3,203,095 3/ 1965 Nelson 30272 3,203,096 8/1965 Beisheim et al. 30272 WILLIAM. FELDMAN, Primary Examiner. IAMES ONES, JR., Examiner, 

1. A DEVICE FOR DRIVING IN ALTERNATE LONGITUDINAL PARALLEL RECIPROCATION RELATIVE TO EACH OTHER A PAIR OF ADJACENT CUTTING BLADES COMPRISING IN COMBINATION, A CASING, AN ELECTRIC MOTOR MOUNTED IN THE CASING, SAID MOTOR HAVING A ROTATABLE SHAFT DISPOSED LONGITUDINALLY OF THE CASING, A WORM ASSOCIATED WITH SAID SHAFT TO BE ROTATED THEREBY, A WORM GEAR CARRIED BY THE CASING AND ENMESHED WITH SAID WORM TO BE ROTATED THEREBY, A PAIR OF PINS EXTENDING FROM OPPOSITE SIDES OF SAID WORM GEAR AND ECCENTRICALLY MOUNTED RELATIVE TO THE AXIS OF THE WORM GEAR TO REVOLVE THEREAROUND, THE SAID PINS BEING ABOUT 180* OUT OF PHASE WITH EACH OTHER IN REVOLVING AROUND SAID WORM GEAR AXIS, A PAIR OF ROCKER ARMS EACH HAVING FIRST AND SECOND SLOTTED PORTIONS AT THE OPPOSITE ENDS THEREOF, PIVOTAL MOUNTING MEANS CARRIED BY SAID CASING FOR PIVOTABLY SUPPORTING EACH ROCKER ARM INTERMEDIATE OF ITS ENDS TO PERMIT THE SAID OPPOSITE ENDS TO SWING IN OPPOSITION TO EACH OTHER, THE FIRST SLOTTED PORTIONS OF SAID ROCKER ARM ACCOMMODATING SAID PINS, RESPECTIVELY, TO CAUSE SAID ARMS TO ROCK ON SAID PIVOTED MOUNTING MEANS UPON THE REVOLVING OF SAID PINS, SAID ARMS ALTERNATELY ROCKING IN OPPOSITE DIRECTIONS UPON THE REVOLVING OF SAID PINS OUT OF PHASE WITH EACH OTHER, A PAIR OF BLADE-ENGAGING ELEMENTS DISPOSED GENERALLY PARALLEL TO EACH OTHER AND EACH BEING ADAPTED TO ENGAGE A SAID BLADE FOR ACTUATING THE SAME, GUIDE MEANS CARRIED BY THE CASING FOR GUIDING ALTERNATE RECIPROCAL PARALLEL MOVEMENTS OF SAID BLADE-ENGAGING ELEMENTS, EACH OF SAID BLADE-ENGAGING ELEMENTS HAVING A PIN EXTENDING THEREFROM AND ACCOMMODATED IN THE SECOND SLOTTED PORTIONS OF SAID ROCKET ARMS, RESPECTIVELY, THE ALTERNATE ROCKING OF SAID ARMS IN OPPOSITE DIRECTIONS CAUSING SAID BLADE-ENGAGING ELEMENTS TO RECIPROCATE ALONG SAID GUIDE MEANS IN OPPOSITE DIRECTIONS WHEREBY CUTTING BLADES ENGAGED TO THE RESPECTIVE BLADE-ENGAGING ELEMENTS ALTERNATELY RECIPROCATE PARALLEL TO EACH OTHER IN OPPOSITE DIRECTIONS. 